In the general field of turbomachines, turbomachines with open rotors have a global architecture that differs from the conventional turbomachine architectures. In fact, as previously recalled, such turbomachines are characterized by the presence of two contrarotating open rotors at the fan.
As an example, FIG. 1 diagrammatically shows, in axial cross-section, a turbomachine 10 of the “open rotor” type, provided with a pair of contrarotating open rotors. The turbomachine 10 comprises, from upstream to downstream, a gas generator 11, a power turbine and a reducer 12, first and second rotors driving the contrarotating open rotors and respectively comprising rotating nacelles 13 and 14 that must be ventilated and pressurized.
The particular architecture of this turbomachine 10 results in obtaining several tight zones, referenced ES, ER, EH et EH′, situated at significant differences from the axis T of the turbomachine 10. Among these, they are first contrarotating tight zones ER and EH, which are formed between two contrarotating bodies respectively belonging to the first and second rotors that drive the contrarotating propellers. Furthermore, there are also tight zones ES and EH′ that are not contrarotating, since they are formed between the stator and the first rotor comprising the rotating nacelle 13. For these tight zones ES and EH′, only the first rotor rotates relative to the stator around the axis T of the turbomachine 10. Furthermore, among these seals, there are tight zones EH and EH′ that are located at the border of lubricant oil enclosures, conversely with respect to the tight zones ES and ER. The tight zone EH′ is formed between the stator and the first rotor, while the tight zone EH, located at the border of the lubricant oil enclosures 15, is formed between the first and second rotors. For the rest of the description, we will more particularly examine the case of the tight zone EH.
In order to allow the lubrication and cooling of the guide bearings of the rotating bodies, the turbomachine 10 traditionally comprises a lubrication circuit. The lubrication circuit is contained in the lubrication enclosure 15 that is arranged inside an air duct C, forming an air duct between the lubrication enclosure 15 and the aerodynamic air flow tunnel V. However, due to the proximity between the lubrication enclosure 15 and the tight zone EH, it is possible that under certain conditions, a flow of oil H may escape from the lubrication enclosure 15 and penetrate the air duct C in an unwanted manner. Furthermore, such a flow of oil H may cause buildups leading to the appearance of oil imbalances in the turbomachine 10 that are detrimental for the considered radii and speeds at such a tight zone EH. In fact, such imbalances may cause an unstable path with significant vibrations on the parts situated downstream from the turbomachine 10, which may cause a risk of damage.
FIG. 2 more particularly shows, according to an enlarged diagrammatic view relative to FIG. 1, the tight zone EH of the turbomachine 10, provided with a labyrinth sealing gasket 16, which is situated at the interface between the lubrication enclosure 15 and the air duct C. Furthermore, FIG. 3 diagrammatically illustrates the oil leak H phenomenon appearing at the tight zone EH during the rotation. More specifically, when the oil H arrives on the second rotating wall 17, inside the lubrication enclosure 15, of the second rotor comprising the rotating nacelle 14, the oil H itself begins to rotate along arrow F1 (direction of rotation of the second rotor), as shown in FIG. 3, at a speed lower than or equal to the speed of the second rotor and then streams toward the maximum radius owing to the centrifugal force. In this way, the oil H is driven by the second wall 17 and arrives on the first wall 18, inside the lubrication enclosure 15, of the first rotor comprising the rotating nacelle 13 with a direction of rotation opposite that of the first wall 18, such that the first and second rotors have opposite directions of rotation. Then, before being driven in the direction of rotation of the first wall 18, the oil H first obtains a zero speed of rotation (reference O in FIG. 3), as a result of which it is only subjected to gravitational force. Thus, the oil H falls and streams along arrow F2 toward the sealing gasket 16 of the tight zone EH. The sealing gasket 16 is then submerged in the oil H. Furthermore, a speed of rotation of the oil H lower than the speed of rotation of the rotor may cause unwanted imbalances to appear.